4. Discussion

I can tell that the bridge did not work because the structure did not support the actual base and the only thing supporting the weight is the base, which was not well formed, so therefore it held only 0kg.

The second design could hold significantly more than the first design because we made the design have more stable to support the base this time. However it failed getting 50kg as one of the sides of the bridge had the supports sticking out from the base because it wasn’t glued properly.

The third design could hold 40kg too, however we have managed to make it lighter and the sides have been glued properly. The reason why it failed was because the structure in between the base and the outside shape was not properly formed, therefore it caused the bridge to only hold 40kg.

The fourth design was lighter and more well formed in terms that the structure was more sturdy and linked to the base. The shape of the bridge was more sturdy than the previous design too. However it held 40kg. The reason the bridge only held 40kg was because the structure had gaps in between them, the structure was hollow and so did not hold as much weight.

This design was both light and it held 50kg. The reason why this bridge is so sturdy is because the shape of the bridge was strong and the structure in-between the base and the outside shape was sturdy and not hollow. The structures were strong and had no gaps in between. In all this bridge had been built in mind with the problems which we had with previous designs. However this bridge failed because the base was crooked because of poor handling by the person that builded it.

4.2 Key findings

Design 1 was not stable as it’s base was not interlocked. The sides did not help the base too.

Therefore in Design 2 we decided to make an arch shape, and form a cross pattern, allowing the mass of the load to be spread across the bridge. We also decided to make the base of the bridge an interlocked design, so that it would be stronger.

In design 3 we where we made the arch bigger and let it face downward, it was not able to fit properly into the advanced load machine, so we had to flip it up.

In design 4 we made the arch of the bridge smaller so it could fit the advance load machine. We made the design of the bridge to be built to face downwards.

During the testing, design 5 was indeed the strongest as the shape of the arch was a triangle and the weight was distributed more evenly.

4.3 Explanation of key findings

Design 1: The sides just added more weight to the bridge, and the load did not help spread it out evenly throughout the bridge. The interlocking of the base makes the weight able to spread out more in the base. The sides needed to support the base too to spread out the force that is exerted onto the bridge by the weight.

Design 2: The bridge was not able to hold more than 40kg due to the sides not glued properly. The connection between the base and the outer surface of the bridge is crucial to spread the force around the bridge.

Design 3: The bridge was too big, so it lead to a structural failure. The bridge had to be flipped upside down so that it could work, therefore it did not work as planned.

Design 4: After the testing we found out that the design was more sturdy than the previous design, but failed, as there were too many gaps in between the structures of the bridge.

Design 5: In our final design. We tried to remove most of the parts, making the bridge the lightest. The arch of the bridge was also in the shape of a triangle allowing the load to be spread across more. The bridge however failed as the base was slightly crooked and failed to make carry more weight.

4.4 Evaluation of Hypothesis

Our hypothesis is correct to say that the lighter the bridge, the more weight it could hold, however it is not right to say that the weight of the bridge was already very heavy and would add on to the weight of the bridge. In fact there are many several reasons that leads to the failure of the bridge. Some of them includes the stability of the bridge, the shape of the bridge, the design of the base and the efficiency rate, which is determined by the weight of the bridge and the amount of load it could hold. The weight of the bridge however only affects the efficiency rate which is the one that shows how well the bridge is build. In conclusion, The weight of the bridge does affect the amount of weight the bridge could hold. The lighter the bridge, with the proper design could lead to a stronger bridge.

4.5 Areas for improvement

There could be more time for us to build up more designs and to collect a more accurate result. We could also experiment with more types of bridge designs instead of focusing too much on the arch design of a bridge. Our bridge could be stronger, if we had used a hot glue gun throughout the process, as hot glue is stronger.